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2.7.2.: Classification criteria

2.7.2.1. Powdered, granular or pasty substances or mixtures (except powders of metals or metal alloys — see 2.7.2.2) shall be classified as readily combustible solids when the time of burning of one or more of the test runs, performed in accordance with the test method described in Part III, sub-section 33.2.1, of the ►M4  UN RTDG ◄ , Manual of Tests and Criteria, is less than 45 seconds or the rate of burning is more than 2,2 mm/s.
2.7.2.2. Powders of metals or metal alloys shall be classified as flammable solids when they can be ignited and the reaction spreads over the whole length of the sample in 10 minutes or less.
2.7.2.3. A flammable solid shall be classified in one of the two categories for this class using Method N.1 as described in 33.2.1 of the ►M4  UN RTDG ◄ , Manual of Tests and Criteria in accordance with Table 2.7.1:


Table 2.7.1

Criteria for flammable solids

Category

Criteria

1

Burning rate test

Substances and mixtures other than metal powders:

(a)  wetted zone does not stop fire and

(b)  burning time < 45 seconds or burning rate > 2,2 mm/s

Metal powders

burning time ≤ 5 minutes

2

Burning rate test

Substances and mixtures other than metal powders:

(a)  wetted zone stops the fire for at least 4 minutes and

(b)  burning time < 45 seconds or burning rate > 2,2 mm/s

Metal powders

burning time > 5 minutes and ≤ 10 minutes

Note 1:

The test shall be performed on the substance or mixture in its physical form as presented. If, for example, for the purposes of supply or transport, the same chemical is to be presented in a physical form different from that which was tested and which is considered likely to materially alter its performance in a classification test, the substance shall also be tested in the new form.

Note 2:

Aerosols shall not be classified as flammable solids; see section 2.3.